Mobile and satellite telephones have gained popularity in recent years in all walks of life. Mobile telephones are not only popular with executives in busy metropolitan areas, but are also popular in sparsely populated areas where the cost, per user, of laying down the infrastructure for traditional wireline telephones is high. Also, people who move their residence from one geographic location to another are beginning to use their mobile telephone number as their residence telephone number to avoid having to notify people of telephone number changes. Significantly lower mobile telephone prices in recent years has also prompted many telecommunication users to use a mobile telephone as their primary residential telephone in lieu of the traditional wireline telephone.
Typical mobile telephone (MT) systems are characterized by dividing a radio coverage area into several smaller coverage areas or “cells” using low power transmitters and coverage-restricted receivers. As shown in U.S. Pat. Nos. 3,906,166 and 4,268,722, which are incorporated by reference herein, the limited coverage area enables the radio channels used in one cell to be reused in another cell. As a mobile telephone in one cell moves across the boundary of the cell and into an adjacent cell, control circuitry associated with the cells detects that the signal strength of the mobile telephone in the just-entered cell is stronger, and communications with the mobile telephone are “handed off” to the just-entered cell. Thus, a system can supply two-way communications for an array of cells, thereby supplying communications for a much wider area than conventional two-way radios.
The terms, mobile telephone, cellular telephone, and radiotelephone are used interchangeably in this application, and they encompass communication devices that use radio signals for communication. The radio signals may be in the spectrum traditionally known as cellular band or PCS (personal communication system) band. The radio signals also may be in any other spectrum assigned for mobile communications. Besides land-based systems, a satellite based communications system also has gained popularity. In the satellite based system, satellite receives signal from satellite telephone network and beams call to satellite telephone. Relatively new, but as prices of these satellite telephones come down, many telecommunication users will begin to use the satellite telephone as their primary residential telephone.
Generally, mobile telephones provide an individual with flexibility, but create an unforeseen problem when used as the primary residential telephone. Traditionally in a residential setting, there are many telephone extensions throughout a user's house. When an incoming call arrives, it rings all the telephone devices connected to the line, and the user can answer the call from any extension.
However, when the mobile telephone is the primary and only telephone in the house, the user must carry the mobile telephone all the time to answer it promptly or run to the mobile telephone every time it rings. Another problem with using a mobile telephone as the primary telephone in any location is that only one person can listen to the conversation. Normally, if there is more than one telephone device connected to a telephone line, there can be one person per telephone device listening and talking to a caller on the other end of the telephone connection. A mobile telephone provides only one device for listening and talking to the other caller. Clearly, it is inconvenient not to allow more than one person to listen to a telephone conversation, and it is even more undesirable to run through the house searching for the mobile telephone every time an incoming call arrives.